Thermal cracking apparatus for hydrocarbonaceous materials of high molecular weight

ABSTRACT

A thermal cracking apparatus for hydrocarbonaceous materials of high molecular weight, wherein an object hydrocarbonaceous material is subjected to thermal cracking in a fluid bed state, the product of said thermal cracking is separated into the overhead fraction and bottom fraction within a column, the resulting overhead fraction is further separated into a liquidphase stream containing substantially no light component and a vapor-phase stream by means of a gas-liquid separator, and said bottom fraction is thermally cracked again by virtue of the combustion heat arising from combustion of said vapor-phase stream, whereby liquid-phase stream is recovered from the gasliquid separator as a thermally cracked oil.

United States Patent Kurihara et al. Sept. 9, 1975 [54] THERMAL CRACKING APPARATUS FOR 3,582,279 6/1971 Bcckman et al. 201/25 HYDROCARBONACEOUS MATERIALS OF 51333 Q P L igaic a. HIGH MOLECULAR WEIGHT 3,736,233 /1973 Sass Ct 211. 201/31 [75] Inventors; Yasuo Kurihara; Masaki Kondo, 3,772,242 11/1973 Liska 201/ both of Tokyo, Japan Primary ExaminerNorman Yudkoff [73] Asslgnee E P snpblljlldmg & J Assistant ExaminerD. Sanders achmery Tokyo Attorney, Agent, or Firm-Woodhams, Blanchard and [22] Filed: Mar. 21, 1974 Flynn [21} Appl. No.: 453,193 [57] ABSTRACT A thermal cracking apparatus for hydrocarbonaceous 1 Foreign Application Priority a materials of high molecular weight, wherein an object Mar. 31, 1973 Japan 48-36895 hydrocarbonaceous material is subjected to thermal cracking in a fluid bed state, the product of said ther- [52] US. Cl 196/116; 208/127 m l r king i epara ed into the overhead fraction [51] Int. Cl. C10G l/07;C10G 7/00 nd t om fracti n w hin 2! l n, he l ing [58] Field of Search 201/3], 25, 25, 27, 28, overhead fraction is further separated into a liquid- 201/29, 30, 36, 37, 202/120, 121; phase stream containing substantially no light compo- 23/262,263, 288 S; 208/127; /8 A, 8 F; nent and a vapor-phase stream by means of a gas- 260/23, 96 D; 196/1 16 liquid separator, and said bottom fraction is thermally cracked again by virtue of the combustion heat arising [56] Referen e Cited from combustion of said vapor-phase stream, whereby UNITED STATES PATENTS liquid-phase stream is recovered from the gas-liquid 3,451,896 6/1969 Schon 201/27 x Sepammr as a thermally cmcked 3,505,201 4/1970 Hodgson ct al 201/31 3 Claims, 1 Drawing Figure PATENTEDSEP ms 3,904,483

THERMAL CRACKING APPARATUS FOR HYDROCARBONACEOUS MATERIALS OF HIGH MOLECULAR WEIGHT BACKGROUND OF THE INVENTION a. Field of the Invention The present invention relates to a thermal cracking apparatus for hydrocarbonaccous materials of high molecular weight. and it relates particularly to an apparatus for the purpose of thermal cracking of chlorinecontaining waste plastics and recovering a thermally cracked oil substantially free of water and/or hydrogen chloride.

b. Description of the Prior Art With the recent increase of tendency to utilize various plastics as packing materials for varieties of articles. the question of how to dispose of waste plastics has come into the limelight as a serious social problem. The disposal of waste plastics usually resorts to thermal cracking of plastics, and for this purpose. the conventional methods have adopted the process comprising thermally cracking the object plastics first and then introducing the resulting cracking products into a condenser to thereby condense the oil content thereof and recover it as a thermally cracked oil. However. such conventional methods are defective in that the thermally cracked oil recovered as above not only is apt to contain varieties of hydrocarbons ranging from a low boiling-point hydrocarbon to a high boiling-point hydrocarbon but also may get mixed with water and/or hydrogen chloride. if contained in the thcrmalcracking products. as hydrochloric acid.

SUMMARY OF THE INVENTION The present invention is intended to provide a ther mal cracking apparatus capable of not only preventing water. hydrogen chloride and/or relatively light hydrocarbons present in the thermal-cracking products from mixing in the thermally cracked oil but also performing thermal cracking of relatively heavy fractions contained in the thermally cracked oil again by utilizing the combustion heat of said relatively light hydrocarbons, thereby rendering recovery of a thermally cracked oil of high quality.

In other words. a thermal cracking apparatus for plastics according to the present invention comprises a fluid-bed type furnace for thermal cracking of plastics. a cracking column for separating exclusively the heavy components of the cracking products being sent therein from said cracking furnace to collect them as the bottom fraction. a gas-liquid separator for cooling the overhead fraction coming in from said column and separating it into a vapor-phase component and a liquid-phase thermally cracked oil. a gas incinerator to burn said vapor-phase component therein. a heat exchanger for effecting heat exchange between the combustion gas coming out of said gas incinerator and the bottom fraction collected in said cracking distillation column to thereby thermally crack said fraction again. and a stripper for stripping said combustion gas subsequent to heat exchange.

BRIEF DESCRIPTION OF THE DRAWING The appended drawing is a schematic representation of apparatus which may be utilized in practicing one embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the appended drawing. waste plastics put in the crusher l are crushed into pieces of about 20 mm square and then supplied to the feeder 3 by means of the conveyor 2. As the feeder in the present embodi ment. a screw feeder is applied. Waste plastics sent in the fluid-bed type cracking furnace 4 through the feeder 3 make self-combustion with the help of air sent in under pressure by the blower 5, and are thermally cracked at a temperature in the range of 450550C. The gas arising in the cracking furnace 4 is separated from carbon and the like within the cyclone 6. and said carbon and the like collected by the cyclone 6 is received in the carbon storage tank 7. The gas arising from cracking is subsequently supplied to the middle of the rectification column 8, where the heavy component consisting of high boiling-point fractions is separated to gather at the bottom of column. The overhead products perfectly free of high boiling-point fractions are sent to the condenser 9 from the top of column. and in this condenser 9, they are cooled down to a temperature a little higher than the dew point of water. whereby fractions corresponding to kerosene and heavy oil are condensed. and then the thus condensed fractions are separated from the vapor-phase component by means of thc gas-liquid separator 10. A part of the separated oil is returned as a reflux to the top of the cracking distillation column through the pump 11, while the rest is recovered into the oil tank 12 as the thermally cracked oil. The foregoing vapor-phase component containing low boiling-point fractions. water. hydrogen chloride or sulfurous acid gas and the like is treated through combustion within the gas incinerator 13.

On the other hand. the aforesaid bottom fraction within the column 8 is subjected to removal of carbon content thereof with the carbon filter 14 and thereafter supplied to the heat exchanger 16 by means of the pump 15. Through heat exchange in this heat exchanger I6 with the offgas coming from the aforesaid gas incinerator. the bottom fraction deprived of carbon as above is subjected to thermal cracking again and is therefore circulated to the column 8. The off-gas passed through the heat exchanger 16 is supplied to the scrubber l7, and hydrogen chloride or sulfurous acid gas contained in said off-gas is absorbed by water being introduced into the stripper by the pump 19 and is taken out into an acid storage tank. The resulting offgas free of hydrogen chloride is discharged into the air through the chimney 20.

As will be understood from the above elucidation. an apparatus according to the present invention not only renders it possible to perform thermal cracking of plastics through a fluid bed having high thermal efficiency but also has such a merit that the high boiling-point fractions among the thermal cracking products can be treated again in the column 8 and that by utilizing the low boiling-point hydrocarbons among the cracking products as the heat source of said thermal cracking. Moreover. according to the present invention. even in the case where hydrogen chloride or sulfurous acid gas is contained in the thermal-cracking products. they can be recovered in the form of hydrochloric acid or sulfuric acid free from oil through the scrubber. In view of these merits. coupled with the effect of recovering a thermally cracked oil of high quality thereof, the apparatus under the present invention deserves to be called a plastic-treating apparatus free of public nuisances.

Further, the thermal cracking apparatus under the present invention may also be utilized in treating waste rubber and other inflammable industrial wastes.

What is claimed is:

l. A thermal cracking apparatus for hydrocarbonaceous materials of high molecular weight, which comprises.

a fluidized-bed cracking furnace having a feed opening for said hydrocarbonaceous material and having an inlet for air so that said hydrocarbonaceous material can be thermally cracked in said furnace at about 450 to 550C, said furnace having an outlet for the gas generated in said furnace; a cyclone having an inlet connected by a first conduit to said furnace outlet and adapted for removing solid particles from said gas, said cyclone having an outlet for purified gas; a rectification column having an inlet for said purified gas connected by a second conduit to said cyclone outlet, said column also having an outlet for high boiling materials at the bottom thereof, an outlet for rectified gas at the upper end thereof and an inlet for reflux at the upper end thereof; a condenser having an inlet connected by a third conduit to said outlet for rectified gas, said condenser having an outlet; a

, gas-liquid separator connected by a fourth conduit to said condenser outlet, said separator having an outlet for gas and an outlet for condensate; means connected between said condensate outlet of said separator and said reflux inlet of said rectification column for feeding a portion of said condensate as reflux to said rectification column and means for removing the remainder of said condensate, as a thermally-cracked oil product; a gas incinerator connected by a fifth conduit to said gas outlet of said separator and adapted for burning said gas from said separator, said incinerator having an outlet for the gaseous products of combustion thereof; a scrubber having a gas inlet connected by a sixth conduit to said incinerator outlet, means for feeding water into said scrubbcr'to contact said gaseous products of combustion supplied from said incinerator and to remove acidic components therefrom, and means for discharging the remainder of said gaseous products of combustion from the scrubber.

2. A thermal cracking apparatus according to claim 1 including a heat exchanger having an inlet connected by a seventh conduit to said outlet for high boiling materials of said rectification column, said heat exchanger having an outlet connected to a further inlet to said rectification column located between the upper and lower ends thereof, said heat exchanger also having an inlet and outlet for heat exchange fluid connected between said incinerator outlet and said scrubber inlet so that said gaseous products of combustion from said incinen ator act as a heating fluid for said high boiling materials.

3. A thermal cracking apparatus according to claim 2 including a filter for removing carbonaceous materials, said filter being connected between said outlet for high boiling materials of said rectification column and said inlet for said high boiling materials to said heat exchanger. 

1. A THERMAL CRACKING APPARATUS FOR HYDROCARBONACEOUS MATERIALS OF HIGH MOLECULAR WEIGHT, WHICH COMPRISES: A FLUIDIZED-BED CRACKING FURNACE HAVING A FEED OPENING FOR SAID HYDROCARBONACEOUS MATERIAL AND HAVING AN INLET FOR AIR SO THAT SAID HYDROCARBONACEOUS MATERIAL CAN BE THERMALLY CRACKED IN SAID FURNACE AT ABOUT 450* TO 550*C, SAID FURNACE HAVING AN OUTLET FOR THE GAS GENERATED IN SAID FURNACE, A CYCLONE HAVING AN INLET CONNECTED BY A FIRST CONDUIT TO SAID FURNACE OUTLET AND ADAPTED FOR REMOVING SOLID PARTICLES FROM SAID GAS, SAID CYCLONE HAVING AN OUTLET FOR PURIFIED GAS, A RECTIFICATION COLUMN HAVING AN INLET FOR SAID PURIFIED GAS CONNECTED BY A SECOND CONDUIT TO SAID CYCLONE OUTLET, SAID COLUMN ALSO HAVING AN OUTLET FOR HIGH BOILING MATERIALS AT THE BOTTOM THEREOF, AN OUTLET FOR RECTIFIED GAS AT THE UPPER END THEREOF AND AN INLET FOR REFLUX AT THE UPPER END THEREOF, A CONDENSER HAVING AN INLET CONNECTED BY A THIRD CONDUIT TO SAID OUTLET FOR RECTIFIED GAS, SAID CONDENSER HAVING AN OUTLET, A GAS-LIQUID SEPARATOR CONNECTED BY A FOURTH CONDUIT TO SAID CONDENSER OUTLET,SAID SEPARATOR HAVING AN OUTLET FOR GAS AND AN OUTLET FOR CONDENSATE, MEANS CONNECTED BETWEEN SAID CONDENSATE OUTLET OF SAID SEPARATOR AND SAID REFLUX INLET OF
 2. A thermal cracking apparatus according to claim 1 including a heat exchanger having an inlet connected by a seventh conduit to said outlet for high boiling materials of said rectification column, said heat exchanger having an outlet connected to a further inlet to said rectification column located between the upper and lower ends thereof, said heat exchanger also having an inlet and outlet for heat exchange fluid connected between said incinerator outlet and said scrubber inlet so that said gaseous products of combustion from said incinerator act as a heating fluid for said high boiling materials.
 3. A thermal cracking apparatus according to claim 2 including a filter for removing carbonaceous materials, said filter being connected between said outlet for high boiling materials of said rectification column and said inlet for said high boiling materials to said heat exchanger. 